Recoil gearing



Oct. 28, 1947.

c. E. BALLEISEN EI'AL RECOIL GEARING' Filed March 7, .1946 3Sheets-Sheet 1 Oct. 28, i947. c. E. BALLEISEN ETAL RECOIL' GEARING FiledMarch 7, 1946 5 Sheets-Sheet I5 KEMW wrm m 7MB. m EB w 4 B W 51 E m E EV Patented Oct. 28, 1947 RECOIL GEARING Charles E. Balleisen, Arlington,and Lafayette B. Hedge, Fairlington, Va.

Application March 7, 1946, Serial No. 652,753

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) 3 Claims.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to us ofany royalty thereon.

The invention relates to gun actions and has for an object to effectimprovement in construction of the bolt and recoil spring devices to theend that a maximum inertia will be available for operation of the saidloading and ejecting mechanism of the machine gun while at the same timethe weight of material required will be greatly reduced, as compared tothat required in prior arms.

A further aim is to simplify the action of the gun so that complexity indriving spring form and mounting will be minimized.

Additional objects include the embodiment of the invention so that itmay be incorporated in small sub-machine guns as well as rifles andlarger arms.

Additional objects, advantages and features of invention reside in theconstruction, arrangement and combination of parts involved in theembodiment of the invention, as will appear or be understood from thefollowing description and accompanying drawings, wherein:

Figure 1 is a perspective view of a small arm in which our invention isembodied;

Figure 2 is a longitudinal vertical sectional view with certain partsthereof in plan view, of said weapon at the instant of impact of thefiring pin upon a cartridge;

Figure 3 is a similar View showing the parts at cocked position;

Figure 4 is a cross-section on the line 44 of Figure 2;

Figure 5 is a perspective view of the bolt and gears with both of thesprings displaced;

Figure 6 is a view similar to Figure 4 showing a modification in which aflywheel element is included.

Referring more particularly to the drawings, there is shown a machinegun which embodies features intended to function in a mannercorresponding to that of the current caliber .45 submachine gun, M3, ofthe United States Army but using a new bolt action and a newconstruction of driving springs. This prior gun is shown in a copendingapplication of Sampson and Hyde, Serial No. 533,569, filed May 1, 1944,for Automatic machine gun, and now Patent No. 2,403,306, issued July 2,1946. The present weapon includes a case portion, or receiver ID, whichis a specially stamped sheet metal assembly, the elements in which maybe made in several parts of suitable number as expediency may dictate.

In the present instance the forward part of the receiver is' providedwith a forwardly pro- J'ecting annular bushing l l into which is screwedthe barrel collar l2 of the M3 gun. As heretofore constructed, thiscollar carries a barrel l3 chambered as in the prior mentioned gun, thecollar being held in assembled position by the usual ratchet !4.Immediately to the rear of the bushing the receiver is formed as ahorizontal chamber bounded by parallel top and bottom plates l5 andIii-l6 the forward parts of which are trapezoidal in plan with sidesconvergent toward the bushing. Vertical side walls I1 join the lateraledges of the plates. At the base of the trapezoid portion the receiveris slightly enlarged to provide semi-circular gear chambers l8 and atthe rear the receiver is narrowed to approximate the width of the baseof the trapezoid portion and extended in uniform width as at [9, closedby a transverse back plate 29. The receiver is of uniform height throughthe parts described, the top and bottom plates conforming to the planshape indicated and the side walls being extended similarly, boundingthe chambers l8 and the rear extension I9. The bottom of the receiver isformed in two parts 16-46 spaced apart at parallel inner edges andflanged downwardly at 21 at these edges so as to form a longitudinalslot 22 between them. A rear hollow grip part 23 is fixed on the lowerpart of the receiver rearwardly of the slot 22, and on the lower forwardpart of the receiver a magazine chute 24 is fixed extending into thereceiver and having a passageway communicating with the space within thereceiver immediately to the rear of the bushing l l. Between the gripand the chute 24 an intermediate housing 25 is set removably, held by atrigger guard 23 sprung thereinto and into the forward side of the gripas in the mentioned sub machine gun. The grip portion may include sideplate parts 21 within the housing 25, in which a trigger 28, sear 29 andconnecting link 39 with the conventional trigger spring 3| are mountedin the machine gun mentioned. The pivot for the trigger comprises onearm of a bail-like piece ,32 one end of which is set through the plates2'! to form a pivot for the trigger while the other end is similarly setthrough the plates 21 to form a trigger stop pin. At its forward partthe housing 25 has an ejector 33 fixed thereon similar inshape andfunction to the ejector in the prior sub machine gun referred to. Theside plates 2? may form continuations of the bottom plates E5 or may beattached, as found expedient. In the present instance a detachable andadjustable wire stock 34 is shown assembled on the gun in the samemanner as heretofore familiar in the sub machine gun mentioned and usinga similar releasable fastening 35.

The top plate of the receiver is formed with a longitudinal narrowcentral slot 36 having a length at least equal to the extent ofreciprocation of the bolt as Will be described. Conventional front andrear sights 37 and 38 are shown on the upper side of the receiver inproper locations.

A bolt 69 is provided, of an isosceles trapezoidal form corresponding tothe shape of the forward part of the receiver. Its forward or apexportion is truncated sufficiently for the formation therein of a recess4| which, when the .bolt is in battery, will fit around the base of acartridge chambered in the barrel; the rear end of the latter beingprojected a distance rearwardly of the bushing H as heretofore. Anextractor 32, the same as that in the bolt of the prior mentioned gun,is mounted in the forward end of the bolt M3 at the upper right handpart. The bolt is slotted on the forward under side as at s3 to permitmovement of the tip of the ejector 33 therethrough and beyond theforward end of the bolt when the latter moves rearwardly. The ejector isat a level above the lower side of an extracted cartridge so as to tiltthe latter and cause its ejection as heretofore. Conventional firing pinand operating means may be mounted in the bolt if desired, but in thepresent instance a fixed firing pin 45 is shown set rigidly at thecenter of the recess i! so that at the instant the bolt moves intobattery the pin will also detonate the primer of a cartridge chamberedin the gun. The bolt is formed with slight downward guide extensions 45at its forward and base parts extending longitudinally and fittedslidably in the slot 22. The lower part of the bolt at its forward partis channelled as at #55 except adjacent the slot t3, where dependingcartridge-pushing lugs 43 are pro-- vided, somewhat wider than the slot43, so as to clear the top round 6% of a magazine clip in the chute 24.The central part of the bolt is recessed as at 6, this recess stoppingshort of the base 47 of the bolt so that the guide 45 thereon at therear may engage rearwardly of the sear when the bolt is moved to cockedpositionf The right and left sides of the bolt are vertical and aretoothed to form respective racks t6 which extend divergently from thefront end of the bolt to its base. While the racks are rectilinear asshown, they may be. otherwise if desired. In the gear chambers l8 thereare mounted eccentric and in the present instance non-circular-gears 49,supported revolubly by pins 59 in the receiver .at such distancelaterally of the bolt that, when the latter is at battery position, thegear portions of minimum radius will be meshed with the respective rackfaces immediately adjacent the base of the bolt, and the developed radiiof the remainder of each gear are progressively greater, so that as thebolt moves rearwardly the gear will remain meshed with the convergentracks throughout movement of the bolt to full recoiled position. Thebolt racks are prevented from running off the gears by any customaryexpedient, a buffer 5i being formally indicated in the rear portion ofthe receiver.

The bottom plates of the receiver are apertured to receive the pins 58therethrough, and on the under side of the receiver respective circularspring cups 52 are secured, these cups havin flat bottoms spaced fromthe plates iii-45' of the receiver, the pins 56 being also revoluble inthe cup bottoms. In the side of each cup a series of vertical slots 53is formed spaced circumferentially as anchorages for the drive springsnow to be described.

Respective spiral torsion band springs 55 are located in each of thecups 52, their inner ends being inserted through suitable slots in thepins 5! while the outer ends of the springs are formed with outwardlyturned hooks 55, each set in one .of the .slots 53 of its respective cup52. By adjusting the spring hooks circumferentially from one slot toanother the driving force of the springs may be regulated in a simplemanner.

The'p'ins may be conventionally keyed in the gears t3, so that on recoilof the bolt rotation of the gear and pins will wind the springs 55 so toplace them under tension or increased tension, tending to reverse themotion of the gears and bolt.

It should be noted that the gears are heavy block bodies and are greaterin dimension in the direction of their axes than would be necessary toafford the necessary gear faces to transmit and overcome the torque ofthe springs shown, the purpose being to gain mass in their operation,increasing the moment of inertia produced at the beginning of recoil ofthe bolt, and at the end of counterrecoil under the-drive of the springs55 as will be further explained.

In Figure 6 there is shown a modification of the invention, in which theconstruction is the same as that before described, excepting that thecups 52 are omitted (although corresponding cups may be included ifdesired), and the springs will be enclosed by recessed flywheels 58, thepins 59 corresponding to the pins 50 being fixed with respective gearsand prings, but also'extended into and keyed with the flywheels. Theouter ends of the springs in the instant case may be hooked upon downturned tongues 6!] struck from the bottom plates of the receiver cover,and extending into the recesses of the flywheels, one or more of thosetongues being provided. for each spring.

The bolt is provided with a cooking knob 6! at the topside, the stem ofwhich is extended upwardly through the slot 36, and the knob portion ofwhich lies close over the top plate of the receiver. By applying manualpressure to this knob when the bolt is at its forward limit of movement,the bolt may be moved rearwardly until its rear lower part wipes overthe sear 29 allowing the latter to spring upwardly into the recess 46and so hold the bolt in cocked position thereafter. I

The forward part of the receiver may be provided with a dischargeopening and binge cover at 62, so that spent cartridges may be ejectedfrom the receiver in operation of the gun as will be described.

In the ordnance art the terms semi-automatic, and automatic aretechnically applied respectively to: (a) an arm which in response tofiring of a round will restore the gun to loaded cocked position readyto five another round at will by manual operation of the trigger: and(b) a weapon which will respond to firing of a round by reloading andrepeating the firing operation continually while the trigger isdepressed.

The use of the term automatic in the appended claims, however, isintended to include semi-automatic as well as full automaticmechsprings.

anisms, and unless otherwise specifically stated the claims are alsointended to include gas op erated and strictly recoil-operatedmechanisms such as the Browning devices, or the Garand, as well asprimer-actuated devices, in which an operating slide or barrel orseparately reciprocating bolt is employed, or both.

In operation, the gun being cocked as before indicated, a clip 63containing a number of rounds 64 may be inserted in the chute 24 frombelow until stopped in the position shown in Figure 3. The head of thetop cartridge then is positioned with its upper head part in the path ofthe depending lugs 43' of the bolt when it next moves to battery underurging of the driving The clip is also formed with its lips inclinedupwardly toward the breech so that the nose of the bullet 65 is furtherelevated above the lower side of the chamber of the barrel this beingthe usual condition with the conventional clip for the mentioned submachine gun. When the trigger is pulled, the bolt is released and isdriven forwardly by the torque transmitted through the gears from thedriving springs 55. It engages the heel of the cartridge above and ateach side of the primer and presses the round forwardly sliding betweenthe lips of the clip, this being inclined upward toward the chamber andthe bullet being supported against the lips of the magazine by thesubjacent rounds and maga i spring as heretofore familiar in the currentsub machine gun cal. .45 M3 of the United States Army. The round engagedby the bolt consequently moves in an upwardly inclined path, so as toenter the chamber of the gun, the rounded nose of the bulletfacilitating this entry, and the flared breech opening of the chamber aswell. Entry of the round into the chamber causes its head end to riseuntil the cartridge is coaxial with the barrel and recess M in the faceof the bolt as the round nearly reaches full chambered position.

Movement of the bolt now continuing, with the head of the cartridgeentering the recess 4!, and the bolt for the moment unimpeded, therecoil face 56 at the bottom of the recess approaches and engages theface of the head at the same time that the extractor 42 snaps past therim of the head and into the groove of the cartridge head.

At the same time that the recoil face of the bolt recess approaches thecartridge head, the firing pin 44 engages the primer, initiatingexplosion of the propellant. Inertia of the bolt and gears will causethe recoil face to press the round home before propagation of theexplosion has developed dangerous pressure in the cartridge, and to alsoadequately oppose reaction of the force exerted against the bullet, sothat movement of the latter is initiated with an effectivenessapproximating that of a locked bolt before the mass of the bolt andgears is overcome. The cartridge is finally pressed rearward, moving thebolt with high acceleration before the bullet leaves the barrel,overcoming the opposition of the driving springs. Further recoil of thebolt continues by the momentum thus imparted thereto, and also by thedriving force of the gears resulting from their -momentum. This windsthe springs to their maximum loaded state as the rear side of the recess46 passes and is engaged behind the sear.

It will be apparent that upon release of the bolt by the sear, theapplication of the torque of the springs is effective with maximummechanical advantage, the teeth of long radius of the gears acting firstagainst the racks, so that a very quick counterrecoil is initiated, andthe progressive decrease of radius of the engaged gear parts thereafterenables the acceleration of the bolt to be sustained with an economicaland highly effective expenditure of energy in accelerating the bolt andmass of the gears and moving them to battery positions. Likewise, uponfiring, recoil may be initiated in the bolt and gears by utilizing thehigh impact value of the cartridge forces at the beginning of recoil sothat these will be effective initially with the highest accelerationvalues, and as effective cartridge pressure on the bolt decreases andthe moment of inertia of the gears is converted to compression of thesprings, the resultant of the moment of the gears is mag nified by theincreasing radius of the gears. Also,

as the resistance of the springs gradually overcomes the momentum of thebolt at the rear part of recoil movement, the greater radius of thegears increases the effectiveness of the springs exponentially as thesprings overcome the gear moments around their axes.

It will be appreciated that the flywheel effect is inherent in the gearsthemselves and the system in either form disclosed has the advantagethat a minimum mass is moved in a straight line, and the reactions dueto movement of the gears oppose each other and so are neutralized. Inconsequence, actual recoil movement of the gun, jump, and vibration,will belargely reduced in this action.

In the application of the invention to practical use, the value of thepropellant and weight of the projectile being known, as well as the timeduring which the projectile is being accelerated in the barrel, areasonable weight for the bolt is determined upon consistent with theforces to be transmitted, work to be done, and shocks of use. This maybe less than required for a simple reciprocating bolt and longitudinallyacting driving spring of the prior'art, and a major part of the body ofthe bolt here shown between the racks may be removed. The mass requiredin the gears or the gears and flywheels, and the radii of the gears andload-depression curve of the springs may then be calculated, based onthe required length of reciprocation of the bolt and the work involvedin loading and ejecting, with suitable margins for casual impedancesfrom various causes.

While we have illustrated our invention in detail in the best embodimentin which it has been completed, it should be understood that this ispurely exemplary, and that its adaptation to other gun actions iscontemplated as within the scope of the invention; and that changes inconstruction shapes and proportions of the parts illustrated,substitution of materials and equivalents, mechanical or otherwise, maybe made without departing from the spirit of the invention set forth inthe appended claims. In the claims, the term fire actuated bolt isintended to denote a bolt which moves reciprocally or otherwise inconsequence of the firing of the piece in which it is incorporated.

We claim:

1. In an automatic firearm having a receiver, a barrel mounted thereonhaving a chamber open through the breech to the receiver, thecombination therein of a bolt reciprocable in the receiver from abattery position at the breech to a recoiled position spaced rearwardlyfrom the breech, said bolt having rearwardly divergent rack elementsfixed therewith at opposite sides, eccentric gears revolubly mounted inthe receiver and'meshing with correspondingly opposed portions of said'racks, said gears being'so constructed and arranged that their parts ofminimum radii are adapted to mesh with the rear portions of the racks,the teeth of the gears being developed on a peripheral curve such thatthe gears remain meshed with the racks throughout movement of the bolt,and respective spring. means for the gears, each said spring having oneend anchored to the receiver and the other'end fixed with one of saidgears, whereby said gears and spring means are adapted to store theenergy of the recoil movement of the bolt and to release said energywith progressively increased mechanical advantage to move said bolt incounterrecoil movement to battery position. 2. The structure of claim 1in which the receiver has a bottom plate, the bolt racks beingconvergent longitudinally of the bolt in one direction, and the gearscorrespondingly eccentric, said gears having shafts fixed therewithextended through the bottom plate of the receiver, each said inclosurebeing a case concentric with the shaft having a plate parallel to thebottom plate and a circular wall normal thereto, said wall having amultiplicity of vertical circumferentially spaced slots therein and eachspring having at (amend a hook end releasably engageable with one slotand its one end attached to, one of said gear shafts.

3. The structure of claim 1 said receiver including a top plate and abottom plate, the racks being convergent longitudinally of the boltforwardly and the gears correspondingly accentric, said gears beingabove said bottom plate on shafts normal thereto, flywheels fixed withthe gears concentric with the axes of rotation of the gears, saidflywheels being next to one of said plates and recessed theretoward anda spiral spring in the recess of each flywheel, each spring having oneend keyed to one of said gear shafts and the other end anchored to thereceiver.

CHARLES E. BALLEISEN. LAFAYETTE B. HEDGE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED. STATES PATENTS Austria -1 May 15,1919

